Accurate, real-time estimation of engine-out emissions is made difficult by the computationally intensive nature of phenomenological engine emissions models, which prevents real-time operation when applied to engine control units (ECU). It is therefore desirable to provide real-time, on-board diesel engine emissions estimation with an empirical, table-based approach that accounts for up to eight (8) input parameters, for optimum emissions estimation under steady-state or transient engine operation. Such emissions estimation is rendered necessary because diesel particulate filters (DPF) controls require some estimation of engine-out NOx (for passive regeneration purposes) and engine-out PM (for filter loading purposes), and no such physical sensors exist, which meet the durability and reliability requirements associated with heavy duty truck applications.
1. Field of the Invention
The present invention relates to a method to provide real-time, on-board diesel engine emission estimation with an empirical, table based approach that accounts for eight (8) parameters, for optimum emissions estimation under steady state or transient engine operation.
2. Detailed Description of the Related Art
Lambert. et al., U.S. Pat. No. 5,431,042 discloses an engine emissions analyzer wherein internal combustion engine emissions information is generated and monitoring engine events that significantly impact engine emissions and by applying the monitored events to a model of the emissions impact of such events. The monitored events and the emissions impact derived from the model are made visible to the engine operator in a real-time format, and further may be made available to a third party through analysis.
Specifically, Lambert, et al., '042 uses presently available operating parameters that may define operating ranges in which the engine emission reduction technology provides a significant emissions reduction benefit are monitored and logged, and are displayed to the engine operator in a substantially real-time format. The logged parameters are periodically applied to a set of predetermined functions derived to map the logged parameters into real-time information on engines emissions, which likewise maybe displayed to the engine operator, for example in a substantially real-time format. The logged parameters may be downloaded to an off board apparatus at prescribed time intervals for application to one or more models to derived engine emissions estimates for the time periods between such intervals.
Buchhop. et al., U.S. Pat. No. 5,703,777 disclose a parametric emissions monitoring system for monitoring stationary engine/compressor units coupled to a pipeline. The system provides in a reciprocating embodiment, reliable and accurate determination levels for NOx, CO and total hydrocarbons from and emissions matrix primarily as a function of engine speed and engine torque. Variations of the determined emissions level is provided by comparing the values of a set of actual engine operating parameters where the respective value in a set of calculated engine operating parameters to determine whether the derivation of the actual operating parameter from the expected operating parameter is within a defined range. That range, and thus whether the engine is operating within a defined control envelope. Each set of engine operating parameters includes spark ignition, timing, fuel rate, and air manifold pressure. When the comparison indicates that the actual engine operating parameters diverge from an expected engine operating parameters, the emission are determined from the emissions matrix, and are subjected to a bios factor being assessed against the NOx, CO, and total hydrocarbon emissions level, the bios factor depending on the severity of the deviation. Moreover, these biased emission levels are further biased relatively up or down depending on selected ambient operating conditions, including relative humidity, power cylinder exhaust temperature deviation, and air manifold temperature.
Li, et al., U.S. Pat. No. 7,212,908 discloses a method for reducing nitrogen oxides and particulate matter in compression ignition emissions. The method includes monitoring at least one engine sensor that generates a signal in response to at least one engine operating condition, and adjusting at least one engine control parameter in response to the signal such that in cylinder spatial distribution of equivalence ratios and temperature is substantially retained to an operating region. The operating region corresponds to a set of equivalence ratio with respect to temperature values that are substantially outside regions supportive of NOx and particulate matter formation. The temperature values are greater than 1650 k, and the equivalence ratios are great than 0.5.